Aniakchak Half Cone Upper Pumice

Start: 570 yBP ± 40 Years [1]

Event Type: Explosive

Event Characteristics:

Description: From Bacon and others (2014): "Pumice-fall and pyroclastic-flow deposits from Half Cone are exposed in the north wall of the 1931 Main Crater 2 km to the south (fig. 13D [in original text]). Here, the cliff at the base of the section (fig. 13E [in original text]) is composed of >22 m of partly welded or indurated coarse pyroclastic-flow material, much like spatter-rich pyroclastic-flow deposits at Santorini (Mellors and Sparks, 1991), containing andesite bombs as large as 0.6 m x 2 m and similar in composition to Half Cone pyroclasts (59 weight percent SiO2). This unit is overlain by 13 m of pumiceous cross-bedded surge layers, 31 m of pumice-fall deposits, 5 m of Half Cone ca. 400 yr B.P. spatter agglutinate, and an 81-m-thick section of 1931 materials (Nicholson and others, 2011, their figure 3F). Dacite tephra older than the Pink Pumice and considered to have a Half Cone source, and which therefore may be correlative with proximal deposits at Half Cone and with the section exposed in the 1931 Main Crater, have weighted mean radiocarbon ages of 840+/-40 and 570+/-40 yr B.P. (tables 1 and 2 [in original text], lower and upper light pumice, respectively)."

References Cited

[1] Postglacial eruptive history, geochemistry, and recent seismicity of Aniakchak Volcano, Alaska, 2014

Bacon, C.R., Neal, C.A., Miller, T.P., McGimsey, R.G., and Nye, C.J., 2014, Postglacial eruptive history, geochemistry, and recent seismicity of Aniakchak Volcano, Alaska: U.S. Geological Survey Professional Paper 1810, 74 p., http://dx.doi.org/10.3133/pp1810, available online at http://pubs.usgs.gov/pp/1810/

[2] Preliminary volcano-hazard assessment for Aniakchak Volcano, Alaska, 2001

Neal, Christina, McGimsey, R. G., Miller, T. P., Riehle, J. R., and Waythomas, C. F., 2001, Preliminary volcano-hazard assessment for Aniakchak Volcano, Alaska: U.S. Geological Survey Open-File Report 00-0519, 35 p.
full-text PDF 24.2 MB

Complete Eruption References

Postglacial eruptive history, geochemistry, and recent seismicity of Aniakchak Volcano, Alaska, 2014

Bacon, C.R., Neal, C.A., Miller, T.P., McGimsey, R.G., and Nye, C.J., 2014, Postglacial eruptive history, geochemistry, and recent seismicity of Aniakchak Volcano, Alaska: U.S. Geological Survey Professional Paper 1810, 74 p., http://dx.doi.org/10.3133/pp1810, available online at http://pubs.usgs.gov/pp/1810/
link to PDFs and tables on USGS website

Preliminary volcano-hazard assessment for Aniakchak Volcano, Alaska, 2001

Neal, Christina, McGimsey, R. G., Miller, T. P., Riehle, J. R., and Waythomas, C. F., 2001, Preliminary volcano-hazard assessment for Aniakchak Volcano, Alaska: U.S. Geological Survey Open-File Report 00-0519, 35 p.
website with links to PDFs
full-text PDF 24.2 MB
map sheet plate PDF (for viewing) 3.1 MB